A user equipment (UE), a mobile station, or a similar component will be referred to herein as a UE. A UE may communicate on an uplink with a base station, an access point, an evolved node B (eNB), a gNB, a transmit/receive point, or a similar component. In some wireless networks, before the UE can transmit on the uplink, the UE needs to send a scheduling request (SR) to the base station requesting resources for the uplink transmission. Responsive to receiving the scheduling request, the base station may provide the UE with an uplink scheduling grant (SG) allocating the resources for the UE to use to transmit data on the uplink.
In some proposed wireless networks, uplink transmissions may occur in a grant-free manner. In the grant-free approach, uplink resources may be preconfigured for and allocated to multiple UEs without the UEs sending scheduling requests. When one of the UEs is ready to transmit on the uplink, the UE can immediately begin transmitting on the preconfigured resources without the need to ask for and receive an uplink scheduling grant. The grant-free approach may reduce signaling overhead and latency compared to the SR/uplink SG approach.
Grant-free uplink transmissions may be suitable for transmitting bursty traffic with short packets from UEs to a base station and/or for transmitting data to the base station in real time or with low latency. Examples of applications in which a grant-free uplink transmission scheme may be utilized include massive machine type communication (m-MTC), ultra-reliable low latency communications (URLLC), smart electric meters, teleprotection in smart grids, and autonomous driving. However, grant-free uplink transmission schemes are not limited to such applications.